Process for obtaining multicolored effect on paper

ABSTRACT

MULTICOLORED EFFECTS ARE OBTAINED ON PAPER BY ADDING A WATER INSOLUBLE, ORGANIC SOLVENT SOLUBLE, COLORANT, SUCH AS SOLVENT VIOLET 11 OR SOLVENT RED 36, TO THE PLUP PRIOR TO THE FORMATION OF THE SHEET OF PAPER, FORMING THE PAPER SHEET AND THEN COATING OR SPRAYING THE PAPER SHEET WITH AN ORGANIC SOLVENT, SUCH AS ETHYL ALCOHOL OR BENZL ALCOHOL, TO DISSOLVE A PORTION OR ALL OF THE COLORANT; ALTERNATIVELY THE COLORANT MAY BE DISPERSED IN AN AQUEOUS SYSTEM AND APPLIED TO THE PAPER SHEET, THE SHEET DRIED AND THEN COATED OR SPRAYED WITH SAID ORGANIC SOLVENT.

United States Patent 3,562,098 PROCESS FOR OBTAINING MULTICOLORED EFFECT ON PAPER Maurice Jacques Plumez, Wheeling, Chester Burton Brown, Chicago, and William Stuart Karro, Franklin, Ill., assignors to Geigy Chemical Corporation, Ardsley, N.Y., a corporation of New York No Drawing. Filed Jan. 16, 1969, Ser. No. 791,798 Int. Cl. D21h 5/02 US. Cl. 162-134 1 Claim ABSTRACT OF THE DISCLOSURE Multicolored effects are obtained on paper by adding a water insoluble, organic solvent soluble, colorant, such as Solvent Violet 11 or Solvent Red 36, to the pulp prior to the formation of the sheet of paper, forming the paper sheet and then coating or spraying the paper sheet with an organic solvent, such as ethyl alcohol or benzyl alcohol, to disssolve a portion or all of the colorant; alternatively the colorant may be dispersed in an aqueous system and applied to the paper sheet, the sheet dried and then coated or sprayed with said organic solvent.

The present invention relates to the coloring of cellulose substrates such as paper. More particularly this invention is directed to a process for obtaining pleasing multicolor effects on paper sheets in a very simple and economical manner in contrast to the presently known practices which generally require many involved steps and thus the resulting paper is very expensive to produce.

This invention provides a very simple process for obtaining such special effects on paper as multicolored spotted, splashed, bleeding madras, and hombre effects. Other effects possible according to the practice of the present invention will become apparent to those skilled in the art from the following description and examples of the invention.

In general this invention comprises adding to a cellulose substrate, in particular paper, a colorant such as a dye or pigment, which colorant is insoluble in water, but soluble in organic solvents, and during or after the drying of the paper to which the colorant has been added, treating the paper with an organic solvent in which the colorant is soluble.

The colorant, which term is also intended to include mixtures of different colorants, may be applied to finished sheets of paper from an aqueous dispersion system in any conventional manner as for example in a size press, coater or by means of a pick-up roll. The sheet is then dried, and either after or during the drying operation the sheet is treated, by means of spraying or coating, with an organic solvent to dissolve at least a portion of the colorant and thus produce a multi-colored effect. The effect achieved of course will vary according to whether a coating of solvent is employed, or if the solvent is sprayed, splashed, or otherwise differentially applied to areas of the paper surface. The particular effect achieved in any one instance of course will depend to a degree upon the kind and amount of colorant present, and the relative speed and degree of solubility of the colorant in the organic solvent. Any necessary adjustment required can readily be made by those familiar with the art of coloring paper after only a few trials with a particular colorant, colorant concentration, solvent, and solvent application means.

The colorant employed alternatively may be added 3,562,098 Patented Feb. 9, 1971 to the paper by addition to the pulp prior to the formation of the sheet. In this case the colorant is added to the pulp mixture in dry powder form. It is preferred that the pulp mixture contain a sizing agent such as resin or a dispersion agent such as for example a condensate of naphthalene sulfonic acid and formaldehyde as disclosed in US. 1,336,759. Generally about 1% by weight of rosin or dispersant has been found to be satisfactory although the amount is not critical and the use of the rosin or dispersant, while preferred, is not absolutely necessary. The pulp is formed into the paper sheet in a conventional manner, and during or after completion of drying the sheet, the organic solvent is applied to at least partially dissolve and develop the colorant.

The colorant in dry powder form may, in another variation, be flicked onto wet sheets and the dye pressed into the sheet and developed in the same manner as in the case where the dye is applied to the pulp slurry.

The colorants which may be employed in the practice of the process of this invention include any water insoluble dye that is soluble in an organic solvent and is ordinarily suitable for coloring paper and development by an organic solvent.

The organic solvents include any solvent in which the colorant employed is soluble and in which it develops and which is otherwise compatible with the paper substrate. The selection of solvent it is apparent of course that the longer a solvent takes to dry the more running or bleeding of dye that will take place and the same is true in consideration of rates and degrees of solubility of a particular dye in a particular solvent. Adjustments to such variations are readily made however after a very few trials by those skilled in the paper coloring art.

Among the solvents which are most often employed are methyl and ethyl alcohol, cyclohexanone, benzyl alcohol, and methyl cellulose.

The dyes are generally employed in amounts of from about 0.01% to 10% by weight of the dry pulp.

The following examples will serve to further illustrate the nature of this invention. It is to be understood that the examples are merely illustrative, and intended to enable those skilled in the art to practice the invention in all of the embodiments flowing therefrom and do not in any way limit the scope of the invention defined in the claims.

EXAMPLE I grams of dry sulfite pulp is slurried in a solution of 7.2 grams 1 liter of alum (17% assay of A1 0 to a total volume of 4 liters. To the slurry is added 0.8 gram of Solvent Violet 11 (CI. 61100) and 1.2 grams of rosin and the slurry agitated for 5-10 minutes. The pulp slurry is diluted to a consistency of 0.4% and a hand sheet formed by suction on an 80 mesh copper screen. The sheets are pressed and dried in a rotating drum dryer. The shees are then sprayed with ethyl alcohol and sheets dried of the solvent alcohol. The resulting sheets exhibit a very attractive spotted violet appearance.

EXAMPLE II The procedure of Example I is repeated but employing Solvent Red 36 (CI. 13900) in place of the Solvent Violet 11 and using benzyl alcohol as the solvent. A pleasing spotted red colored paper is obtained.

EXAMPLE III Paper sheet is formed as in Example I, except that the dye is not added to the pulp slurry. After the paper sheet is formed and dried, an aqueous dispersion of 1% by weight of Solvent Violet 11 and the naphthalene sulfonic acid-formaldehyde condensation product of U.S. 1,336,759 is applied to the surface of the paper sheet by means of a pick-up roll and the sheet again dried. The sheet is then sprayed with solvent as in Example I with generally similar results being obtained.

What we claim is:

1. A process for obtaining a multicolored effect on a paper which comprises adding to the paper pulp in dry powder form, or in an aqueous dispersion, a water in soluble, organic solvent soluble, colorant, forming a paper web from said pulp, and then applying to said formed web an organic solvent in which said colorant is soluble, to thereby achieve a multicolored effect on said paper.

References Cited UNITED STATES PATENTS 1,889,953 12/1932 Dankert 162-134 2,030,483 2/1936 Vong 162-184 2,273,305 2/ 1942 Whitehead 8-14 OTHER REFERENCES Casey, Pulp and Paper, Vat Colors, vol. 3, page 1225.

10 S. LEON BASHORE, Primary Examiner R. H. ANDERSON, Assistant Examiner U.S. C1. X.R. 

